Isla Grande

Isla Grande is the answer to the complaint almost every first time visitor to Cartagena eventually makes, which is that the city beaches are grey and murky. The largest of the Rosario Islands, Isla Grande sits about an hour by boat off the coast inside a protected national park, and the water out here is a different world, translucent turquoise that decades of reef conservation have brought back. If you want the postcard Caribbean near Cartagena, this is where you go, and you go by boat.

Be clear eyed about what the island is. This is not a long strand of open public sand with a town behind it. It is a low, green island fringed with small sandy pockets and a cluster of beach clubs and eco lodges, so the day is built around the water and a lounger rather than a wide beach walk. Most visitors come on a day trip and buy a beach club day pass, which typically bundles a lounger, lunch and sometimes the boat transfer. There are several clubs to choose from, including well established names like Mangata and others around the island, and the vibe ranges from calm and family friendly to livelier party boats, so pick the operator to match the day you want. Prices and exactly what each pass includes change often, so confirm before you book.

Play it right and it is a wonderful day. Take an earlier boat to beat the crowds and the midday heat, snorkel over the recovered reef while the water is stillest, then settle in for a slow seafood lunch before the afternoon boats head back. Bring cash, since card service is patchy, reef safe sunscreen for the national park, and a little patience for island time. The catch is simply that it is a committed boat day with costs that add up, so it rewards planning. For clear water near Cartagena, though, nothing on the mainland comes close.